The present invention relates to a connecting adapter and particularly, to a connecting adapter for a resistance welding electrode configured to mate on opposite ends with a standard adapter shank and a standard welding electrode.
Resistance welding is used widely to join metal pieces together by electrically inducing localized fusion of the metal. Generally, a pair of metal sheets is overlapped, and then opposed electrodes are brought in from either side to exert substantial pressure on the overlapping joint. A very high current is then passed between the electrodes. Due to current flow resistance at the joint, substantial heat is generated at the spot pressed between electrodes, which fuses together the metal sheets.
A resistance welding system comprises a high voltage power supply, a source of fluid cooling unit, and a robotic arm to which a welding shank attaches. A welding electrode having a central internal cavity is mounted on the welding shank by pressing the electrode over a tapered portion at an end of the shank. A resistance-welding electrode is typically made from copper, is generally elongated in shape, and typically has a tapered exterior tip. The standard resistance welding shank is generally an elongated hollow body with a defined central cavity, and is typically made of zirconium copper, chrome copper or dispersion strengthened copper. Cooling fluid is supplied to the central cavity of the resistance-welding electrode through the central cavity of the standard shank during the welding operation to limit heating of the electrode and softening and deformation of the electrode that would otherwise result.
The tip of the welding electrode, which contacts the metal workpiece, wears by spreading or xe2x80x9cmushroomingxe2x80x9d deformation. Overtime, the electrode will wear sufficiently that it must be replaced. Repeatedly replacing electrodes will, in turn, cause the taper portion of the adapter shank to wear to the point where the adapter shank must also be replaced. The adapter shank normally outlasts electrodes by a ratio of 10:1. However, since the cost of a standard adapter shank can be significant, depending upon the material and length of the shank, minimizing shank wear and replacement are highly desirable.
Therefore, there is a need for a device, which is mountable between the standard resistance adapter shank and the standard resistance welding electrode, to protect the standard resistance welding adapter shank from the wear that would otherwise result from repeated electrode replacement.
The present invention provides a connecting adapter that reduces the wear to which a standard resistance welding adapter shank would otherwise be subjected. The connecting adapter is used with a resistance welding electrode having an attachment end portion and a resistance welding shank having a mounting end portion. The connecting adapter is comprised an elongated body wall of electrically conductive metal having a proximal end portion and an integral distal end portion. The proximal end portion of the body has a shank attachment structure that is adapted to be mounted in an electrical conducting and mechanically supported relation to the mounting end portion of the shank. The distal end portion of the body has an electrode attachment structure that is adapted to be attached in an electrically conducting and mechanically supported relation to the attachment end portion of the electrode.
In a first portion of the connecting adapter of the present invention, the outer surface of the body wall is shaped to match an exterior surface of a standard welding adapter shank. A through-bore defined by the inner surfaces, in the first portion of the connecting adapter is sized to accommodate there within the end of the welding shank designed to receive the welding electrode. In a second portion of the connecting adapter, the outer surface is tapered down in diameter from the first portion in order to allow the electrode to mount thereon. The through-bore in the second portion of the connecting adapter, as defined by the inner surfaces, is sized to match the interior diameter of a standard welding shank.
The connecting adapter having two differently shaped portions allows the mounting of a standard adapter shank at one end of the connecting adapter and a standard welding electrode at another opposed end of the connecting adapter. It is to be appreciated that because the connecting adapter is mounted between the adapter shank and the welding electrode, the connecting adapter protects the welding shank from wear. Additionally, since the connecting adapter is formed of a wear-resistant material, it is replaced only periodically, further reducing the wear on the more expensive standard adapter shank.
The connecting adapter is formed on a high-speed, five-die, cold former. Such a manufacturing process allows the production of an economical strength hardened adapter. It is to be appreciated that the connecting adapter is made of zirconium copper or dispersion strengthened copper or any other suitable material that provides high electrical conductivity, anneal resistance, and resistance to wear and deformation.
It is an object of the present invention to provide a device that is configured to mate on opposite ends with a standard resistance welding adapter shank and a standard resistance welding electrode, to protect the welding adapter shank from wear. It is another object of the present invention to provide a connecting adapter that fits over an end portion of a standard resistance welding shank and fits into a cavity portion of a standard welding electrode.
Further objects and advantages of the invention can be ascertained by reference to the specification and drawings herein which are by way of example only and not in limitation of the invention which is defined by the claims and equivalents thereto.